Virtual Engineering of a Fusion Reactor: Application to Divertor Design, Manufacture, and Testing

Virtual engineering is being widely adopted in diverse technical fields and has the potential to accelerate the realization of tokamak fusion energy. In this paper, we demonstrate, for the first time, the use of virtual engineering techniques to enhance the development cycle of a water-cooled divertor plasma facing component. The divertor concept under development is the thermal break, which aims to increase heat flux limits and DEMO-relevance by alleviating the high thermal mismatch stress between a tungsten monoblock and a copper alloy cooling pipe. Response surface-based design search and optimization is used to explore the potential of the concept and to inform the design of a high-heat-flux (HHF) mock-up. In developing a brazing manufacturing procedure, computed tomography scanning and subsequent image-based finite-element modeling revealed a defective joining process which would result in unacceptable divertor performance. The same techniques were used to develop an improved brazing procedure that was used to manufacture the mock-ups. A production defect was discovered by ultrasonic qualification testing, but a "virtual twin" model confirmed the acceptable performance of the mock-up under HHF. Indeed, all mock-ups were then subjected to at least 100 cycles of 20 MW/m(2) HHF testing, with no signs of damage. The development of these virtual engineering and modeling techniques will facilitate criteria for design and component rejection, and in future enable predictive maintenance of components in service. Practical trials and experiments will remain essential to complement and validate simulations.